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This article addresses input issues exclusively. Please see the Troubleshooting Gameplay and Performance article if you are encountering poor game performance (for example, choppy video display and occasional stalling).


Common symptoms of mouse and keyboard lag include delayed response time on movement and firing controls (for example, one's player keeps moving or firing for several moments after one has released the key or mouse button to move or fire).

General Recommendations

  • Windows Vista/7 Mouse Options
    1. Go to the Start > Control Panel > Mouse
    2. Click on the Pointer Options tab
    3. Ensure that Display Pointer Trails, Smart Move, and Acceleration in Games options are disabled (some of these options may not be displayed, depending upon which version of Windows you are using)
    4. Exit the Mouse Properties window by clicking OK to save your changes
  • Windows Vista/7 Accessibility Options
    1. Go to the Start > Control Panel > Ease of Access Center
    2. Click on Make the keyboard easier to use
    3. Ensure that Turn on StickyKeys, Turn on FilterKeys, and Turn on ToggleKeys options are disabled
    4. Click on Set up Stickey Keys and Set up Filter Keys and uncheck the Turn on Sticky Keys when SHIFT is pressed five times and Turn on Filter Keys when SHIFT is pressed for 8 seconds options and click Apply
    5. Exit the Ease of Access Center window by clicking OK to save your changes
  • Windows XP Mouse Options
    1. Go to the Start > Settings > Control Panel
    2. Select the Mouse icon
    3. Click on the Pointer Options tab
    4. Ensure that Display Pointer Trails, Smart Move, and Acceleration in Games options are disabled (some of these options may not be displayed, depending upon which version of Windows you are using)
    5. Exit the Mouse Properties window by clicking OK to save your changes
  • Windows XP Accessibility Options
    1. Go to the Start button and select Settings, then Control Panel
    2. Select the Accessibility Options icon
    3. Ensure that Use StickyKeys, Use FilterKeys, and Use ToggleKeys options are disabled
    4. Click the Settings button for each option and uncheck the Use Shortcut option and click OK
    5. Exit the Accessibility Options window by clicking OK to save your changes
  • HL Mouse Filter

    You may set this filter in the game console by entering m_filter 1

  • vgui_emulatemouse

    This is an HL option that forces a software mouse cursor emulation (this may be useful for older graphics cards which display a flickering mouse cursor). Enter vgui_emulatemouse 1 in the console to enable this feature.

ATI Users

The ATI Catalyst drivers include an ATI HotKey Poller service that has been reported to cause input lag on certain system configurations. If you do not overclock your video card or otherwise use the ATI hotkeys, it is recommend that you disable this service if you are experiencing input lag in games. To disable the service, please follow these directions:

  1. Click Start -> Run
  2. Type Services.msc and press Enter
  3. Find the service "ATI HotKey Poller"
  4. Right-Click on the service and select Properties
  5. Change "Startup type" to Disabled
  6. Click "Apply", then "Ok"
  7. Reboot your computer


PS/2 Peripherals

  • Revert to the Default Mouse Drivers

    Uninstall any specialty mouse drivers and allow Windows to detect and install the default mouse drivers.


USB Peripherals

  • Interference from Other Peripherals

    If you have other USB peripherals plugged in (for example, a digital camera, USB disk drive, or USB sound or video capture device), please try unplugging the non-essential USB devices when playing.

    Avoid using USB hubs to connect your mouse and keyboard - plug directly into the back of the computer to ensure the best performance.

  • USB Power Saving Mode

    If you're experiencing mouse lockups or failures, it may be because your computer is automatically turning off the power to a USB Root Hub.

    1. Go to your Control Panel > System > Hardware tab > and click on the "Device Manager" button.
    2. In the Device Manager window, find the item or items labeled "Universal Serial Bus controllers." Open it, and double-click the first item called "USB Root Hub."
    3. In the USB Root Hub Properties dialog, click on the "Power Management" tab.
    4. "Allow the computer to turn off this device to save power" is checked by default. Uncheck this box, and click "OK."
  • Test USB performance against PS/2 performance

    If you continue to encounter issues with USB mouse performance, please try using an adapter (many USB mice come with a PS2 adapter) to plug into the PS/2 port. (You may also try using a generic two-button PS/2 mouse to help determine if the issue is specific to USB input.)


Wireless Peripherals

  • Replace Batteries

    Please ensure you have fresh batteries installed in any wireless peripherals as a preliminary troubleshooting step.

  • Update Drivers

    Ensure that you have the latest drivers from your wireless peripheral manufacturer.

  • Test Wireless performance against PS/2 performance

    Try using a generic two-button PS/2 mouse to help determine if the issue is specific to wireless input.

When configuring your mouse for use in games it is important to note that there are four different programs or components involved in interpreting and controlling how your mouse moves and what it does:

  1. BIOS

    Your motherboard BIOS has a set of unique routines that make the mouse operate, one set in PS2, the other set in USB.

  2. Operating System

    The operating system has a core set of drivers that own your mouse, how it moves, how it clicks, how fast it moves, what the cursors look like, how to interpret buttons.

    On the surface there appears to be only one driver set, but in reality there are three unique driver sets, one for PS2 and one for USB (which has many things going on), and then there is the API or Application Interface on top of those that takes a generic set of commands and translates them back and forth to fit the specific language that your mouse hardware speaks.

    OK, so now we've arrived at the desktop and the mouse has a number of attributes that you set in the control panel.

    • How fast the mouse cursor moves relative to the physical mouse ... this is "speed"
    • How fast the mouse moves relative to how fast you physically move the mouse, this is "acceleration" ... move the mouse fast and on the screen it starts out slow, speeds up and then slows down again. Acceleration is a feature that lets you move across the screen quickly but not lose control. Without acceleration, you might have to pick the mouse up and re-position it on the pad before you can get to the other side of the screen.
    • Buttons - all the different functions you can set you buttons to do - most of which are not suitable for playing Half-life.
  3. Mouse Manufacturer (Custom Drivers and Driver Extensions)

    Mouse manufacturers create drivers that let the mouse do a lot more then just point and click, they want the mouse to be a highly integrated control device and a unique part of the program you are running.

    Unfortunately, many of these programmatic extensions (and the drivers themselves) just add wierd delays and unnecessary processing when you are in the game.

    Half-Life has it's own set of drivers for the mouse and keyboard which talk directly to the Mouse API within the Operating System ... unless the mouse drivers and extensions are hijacking the mouse first. It is there that weird things can happen.

    Ideally, the very best setup is the O/S and mouse drivers get the heck out of the way and let HL totally control the mouse and keyboard.

    Unfortunately, HL can't possibly understand all the hundreds (or thousands) of mouse designs so the unique drivers for the mouse hardware have to have an interpretive layer above it (again the API).

  4. USB HUBs, Batteries and Power Saving Features

    One additional thing to remember is that motherboards and the operating system have several levels of power savings available. Especially on notebook computers, you may find that your USB power might be getting disabled to save power while you are playing!

    Wireless Keyboards and Mice have batteries which can run out or get low so they can start acting odd too.


Console Commands for Mouse Configuration

Here are the three commandline (launch option) switches you can add to change how HL manages your mouse behavior and properties:

  • -noforcemparms (use desktop mouse buttons settings)

    This setting tells HL to use whatever button assignments you have set in the mouse properties. You have to make sure each button has a letter or function-key assignment appropriate for the game.

    Normally HL forces it's own set of button definitions onto the mouse and when you return to the O/S all the buttons return to your operating system setup. This switch turns that off.

  • -noforcemaccel (use desktop mouse acceleration settings)

    Normally in HL the last thing you want is acceleration. Sometimes the HL no-acceleration control won't work because the mouse or its drivers are too different.

    This switch tells HL to bugger off trying to manage the acceleration and whatever you have set in the mouse properties for the desktop is what will happen in the game.

  • -noforcemspd (use desktop mouse speed settings)

    This tells HL to use the speed settings you have set on your desktop. Whatever you set in your mouse properties is how it will behave in HL.

    This is separate from the "sensitivity" setting in your mouse properties, think of the sensitivity as an amplifier, it can attenuate the movement, leave it exactly the same or amplify it.


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